1. Field of the Invention
Provided are cationic lipids that bind and transport polynucleotides, polypeptides, pharmaceutical substances and other biologically active species through membrane barriers. More specifically, symmetrical diamine cationic lipids are disclosed that complex with selected molecular species and facilitate delivery of those selected species into and through membranes and comparable boundary structures.
2. Description of the Background Art
Cellular transfection strategies for gene therapy and similar goals have been designed and performed, but many of these procedures involve recombinant virus vectors and various problems exist with these viral gene transfer systems. Even generally advantageous adenovirus techniques encounter difficulties since most humans have antibodies to many of the adenovirus serogroups, including those that have been chosen as vectors. Wild type adenoviral superinfection of an adenoviral vector treated patient may result in propagating the recombinant vector as a defective viral particle, with the ability to infect many unintended individuals (if chosen to have a rare serogroup). The chance of adenoviral contamination is quite low but not impossible. The safety of using these genetic materials in humans remains unclear and thus hazardous.
Safe, non-viral vector methods for transfection or gene therapy are essential. A few such safe lipid delivery systems for transporting DNA, proteins, and other chemical materials across membrane boundaries have been synthesized by research groups and business entities. Most of the synthesis schemes are relatively complex and generate transporters having only limited transfection abilities. A need exists in the field of cationic lipid transporters for cationic species that have a high biopolymer transport efficiency. It has been known for some time that quaternary ammonium derivatized (cationic)liposomes spontaneously associate with DNA, fuse with cell membranes, and deliver the DNA into the cytoplasm. LIPOFECTIN.TM. represents a first generation of cationic liposome formulation development. LIPOFECTIN.TM. is composed of a 1:1 formulation of the quaternary ammonium containing compound DOTMA and dioleoylphosphatidylethanolamine sonicated into small unilamellar vesicles in water. One problem with LIPOFECTIN.TM. is that it contains non-metabolizable ether bonds. Other problems with LIPOFECTIN.TM. are an inhibition of protein kinase C activity and direct cytotoxicity. In response to these problems, a number of other related compounds have been developed. The diamine compounds of the subject invention improve upon the capabilities of existing cationic transporters and serve as very efficient delivery means for biologically active chemicals.
As indicated immediately above, various cationic lipids have been synthesized in previous references. For example, U.S. Pat. No. 4,812,449 discloses in situ active compound assembly of biologically active agents at target locations in preference to surroundings which are desired to be unaffected. Several charged and uncharged amine derivatives are described.
Introduced in U.S. Pat. No. 5,171,678 are lipopolyamines and their use for transfecting eukaryotic cells. A polynucleotide is mixed with the subject lipopolyamine and contacted with the cells to be treated.
U.S. Pat. Nos. 5,186,923 and 5,277,897 relate an enhancement of cellular accumulation of lipophilic cationic organometallic compounds by reduction of the intramembrane potential. Technetium containing compounds are disclosed.
Lipophilic cationic compounds are presented in U.S. Pat. No. 5,208,036. Asymmetrical amine compounds are synthesized and employed in a method for DNA transfection.
U.S. Pat No. 5,264,618 discloses cationic lipids for intracellular delivery of biologically active molecules. Asymmetric ammonium containing cationic lipids are presented for transporting molecules into membranes enclosed systems.
Transfection of nucleic acids into animal cells via a neutral lipid and a cationic lipid is revealed in U.S. Pat No. 5,279,833. Liposomes with nucleic acid transfection activity are formed from the neutral lipid and the ammonium salt containing cationic lipid.
U.S. Pat No. 5,334,761 describes other amine containing cationic lipids are reported. Cationic lipids are utilized to form aggregates for delivery of macromolecules and other compounds into cells.
The foregoing patents reflect the state of the art of which the applicants are aware and are tendered with the view toward discharging applicants'acknowledged duty of candor in disclosing information which may be pertinent in the examination of this application. It is respectfully submitted, however, that none of these patents teach or render obvious, singly or when considered in combination, applicants'claimed invention.